空间约束下多关节机械臂架末端柔顺控制方法

A Flexibility Control Method for the End of a Multi Joint Mechanical Arm Under Spatial Constraints

多关节机械臂的运动具有惯性和延迟特性,由于机械臂的质量分布和关节间的连接方式等因素,导致当控制信号发生快速变化时,机械臂需要一定的时间来响应并改变自身的状态。这种延迟导致机械臂在控制过程中出现过度振荡现象,从而严重影响机械臂的控制精度。为满足该类型机械臂良好的动态响应能力,以空间约束为前提条件,设计一种新的柔顺控制方法。根据多关节机械臂的驱动机构结构,计算机械臂末端与物体间直线距离。将其作为末端位置的限制参量,建立闭环向量约束方程。基于最小能量法设计全局搜索策略,对机械臂运动轨迹实现约束。基于此,结合比例-积分-微分控制技术(Proportional-Integral-Differential,PID)与递推最小二乘法,设计臂架末端的柔顺控制方法。在模拟场景与真实场景中分别完成研究方法的性能测试。测试结果显示,该方法控制下的末端移动轨迹更佳,回形和环形轨道上的平均误差仅有0.954mm、1.036mm,多关节机械臂架的真实应用场景下,研究方法控制下机械臂末端安装的螺栓轴线与栓孔轴线间的水平偏差仅有0.23mm,控制精准度能够保证高精度操作任务的准确完成。

The motion of a multi-joint robotic arm exhibits inertia and delay characteristics.This is due to factors such as the mass distribution of the arm and the method of connection between the joints,which result in a certain amount of time required for the arm to respond and change its state when the control signal undergoes rapid changes.This delay causes the robot arm to experience excessive oscillation during the control process,thereby significantly affecting the precision of the arm′s movement.To meet the good dynamic response ability of this type of robotic arm,a new compliance control method is designed based on spatial constraints.According to the driving mechanism structure of the multi-joint manipulator,the linear distance between the end of the manipulator and the object is calculated.The closed loop vector constraint equation is established by taking it as the limiting parameter of terminal position.A global search strategy is designed based on the minimum energy method to implement constraints on the trajectory of the manipulator.Based on this,proportional integral differential(PID)and recursive least square method are combined to design the compliant control method of the end of the boom.The performance test of the research method was completed in the simulated scenario and the real scenario respectively.The test results show that the end movement trajectory under the control of this method is better,and the average error on the loop and annular track is only 0.954mm and 1.036mm.In the real application scenario of multi-joint mechanical boom,the horizontal deviation between the bolt axis installed at the end of the manipulator and the bolt hole axis under the control of the research method is only 0.23mm.Control accuracy can ensure the accurate completion of high-precision operation tasks.